Remarks:
Be sure you are in the "model" module (press 1)
This tutorial works in SOFTIMAGE|XSI 1.5 and above only

Download the scene here: SCENE

See an animation created with this tutorial: ANIMATION

Start with a polymesh sphere: Get -> Primitive -> Polygon Mesh -> Sphere

Set this value: Extent (Angles) End V: 90

You should have exactly half of a sphere.

Duplicate that sphere and scale it by -1 on the Y axis.

You should now have a perfect sphere from 2 identical halves.

Next, select one half, click: Create -> Poly.Mesh -> Merge, then select the second half.

Set the Tolerance to 10.

(This allows stretching between the two objects when you move them apart)

You should now have 3 objects: The upper sphere half, the lower sphere half, and the final merged sphere. In the Explorer view, I re-named them so it should look something like this:

Select the metaball object in the explorer and move it to the right side of the two halves.

(You can smooth out the metaball a little by upping the subdivision level)

It should look something like this.

Ok, so now you have your two sphere halves which control your metaball, and you have your metaball which will stretch whenever you move your control spheres.

Now when you move your top control sphere up, it should look like this:

So we now have a metaball-like object that which will stretch, but it won’t look right unless it starts to pinch in the middle when the control spheres move farther apart.

Remember that first step in this tutorial where we had to set the End V to 90?

All we have to do is animate that.

First animate the top control sphere to move up by keyframing its movement on the Y axis.

(make sure both halves are at 0 on the Y axis when you set the first keyframe)

Now move the animation keyframe slider to 100

and translate the upper sphere half up in the Y axis by 18 units.

(at this point I also changed the color of the metaball so it’s easier to see)

Move the animation playback slider to frame 10.

Select the top control sphere half and hit Enter.

Set a keyframe for the End V by clicking the green box next to it.

It will turn red like this:

(it should also still be at 90 like this)

Follow this same step for the lower sphere half (keyframe it on 10).

Ok, now for the final step, move the animation keyframe slider to frame 70.

Select the top sphere half again and hit Enter.

Move the End V Slider all the way up to 180 and keyframe it.

Do the same for the lower sphere half (keyframe it at 100 with the End V at 180).

Now when you move your animation keyframe slider up and down you will see the two spheres morph in and out of each other just like real metaballs!

Now you can hide the control spheres so all you see are the red meatballs.

This would be very useful for cells and organisms splitting, or water drops, or lava lamps, etc.

Tutorial by: Paul Ehreth

Website: www.paulehreth.cjb.net

Email: PlanetSun@juno.com